Southern Bluefin Tuna are large, fast, pelagic predators and as such probably have a very different metabolism to most other species of cultured finfish. There is a need therefore, to develop a comprehensive understanding of the metabolic rates of SBT as a basis for improving our management and husbandry of this species.

Nutrition (food conversion ratios), responses to water quality (limiting oxygen concentrations), response to predators, fish health and environmental outcomes (e.g. waste production) are all linked to metabolic rate. Improving the management of fish in culture including the development of new feeds, optimising production and product quality and assuring sound environmental outcomes are all dependant on developing this basic knowledge.

At the Southern Bluefin Tuna (SBT) Aquaculture Subprogram Steering Committee Workshop, held on the 6th November 2002 in Port Lincoln, physiology was identified, by both industry and research sectors, as a major research priority. In particular, it was recognised that a need exists to measure SBT size-specific metabolic rates under a variety of circumstances, including tow history, handling, cage acclimation effects, water temperature, changes in oxygen levels (especially hypoxia), levels of cage fouling, feeding activity and food type. Similarly, data on SBT’s metabolic responses to stressors such as microalgae, sediment, noise and predator presence were also considered important.

This project will also provide invaluable information about metabolic rates that will inform research being conducted on the species in the wild and thereby enhance our understanding of the overall biology of this species. Importantly, the data could be used to calibrate information from tagged fish currently being collected as part of CSIRO’s ongoing research into the movement and ecology of SBT using archival tags.

The project will address Industry needs by producing the following outcomes:
· Measurements of oxygen consumption on commercial-sized SBT
· Incorporation of those data into metabolic model for cultured SBT
· An investigation of the usefulness of microsensor technology in monitoring tuna respiration in a commercial environment.

Four of the eight fishing industry sectors have identified pollution as one of the priorities for improvement. Although the pollution types and sources were not further defined, the impacts from persistent organic pollutants are becoming more common worldwide. Toxic effects arising from exposure to chemical pollutants are frequently reported. In addition, contamination by these chemicals can lead to discrimination and/or rejection of the product in the marketplace. The need is for a properly funded study that examines the quality of inshore seawater in a defined area and from which links can be established between cause and effect. For the reasons set out below, the study proposed is seen as Stage 1 of a multi-stage process which will enable the Fishing Industry to understand where it stands currently as far as water pollution by organic chemicals is concerned and the impacts these chemicals might have on specific ecosystem components.

The focus of stage 2 would be to examine the impact of bio-available inorganic chemicals and, separately, increased levels of nutrients on specified key ecosystem components. A subsequent stage could examine the impact of identified industrial chemicals on appropriate indicator species. The aim must be to appreciate the sensitivity of (South) Australian marine ecosystems to pollution from a variety of sources and the impact on market share.

Stage 1.
There is increasing evidence from other States in Australia, and worldwide, that persistent herbicides arising from terrestrial activities are impacting on the growth and productivity of inshore seagrass beds. The toxicity of agricultural chemicals, principally insecticides, has been demonstrated on fish species that are indigenous to the Northern Hemisphere but no study has looked at the toxicity of persistent agricultural chemicals to species found in Australia. And, more importantly, the toxicity of widely used persistent agricultural chemicals to species of commercial importance in South Australia has not been studied.

Recruitment of juveniles from the inshore nursery areas where persistent agricultural chemicals are most likely to be found could be significantly compromised. Modern pesticides, intended for terrestrial use, are toxic at extremely low concentrations.

The levels of persistent herbicides found in marine environments elsewhere in the world are significant, and similar levels would be expected to occur in Australian inshore waters given the extensive use of herbicides in Australian agriculture. The toxicity of persistent herbicides to inter-tidal seagrass species has not been studied in Australia.

A study linking the concentration of a key persistent organic insecticide in the soil, its concentration in the adjacent marine environment and its toxicity to a key marine indicator species such as the prawn, represents a good model for the study of the impact of a non-point source pollutant over a relatively small area.

The contribution by wind-blown topsoil from adjacent farm areas, which can act as a carrier of considerable quantities of adsorbed persistent organic pesticides has not been examined in South Australia. The role of dust-storm events in the transport of toxic chemicals elsewhere in the world is recognised. The concentration in seawater of persistent organic pollutants such as insecticides has not been determined on a seasonal basis.
Dose-response data for a major persistent insecticide and a key indicator marine species such as prawns, combined with knowledge of the concentration of the pesticide in seawater, will provide a scientific basis for proposing modification of land management practices.

The demonstration of significant levels of persistent pesticides in fine farm topsoil and identification of those pesticides in seawater, combined with demonstrated toxicity effects on a key marine species of commercial significance, would provide further support for proposing changes in land-care strategies designed to mitigate these inputs.

The need for a coordinated sub-program, and research projects focussing on collection and neutrality, nutrition, health and system design and handling has been outlined in the background to this submission. Further evidence of the need for this and the other sub-program projects includes:

Project 1: COORDINATION AND SUB-PROGRAM MANAGEMENT: At a planning workshop in Hobart in 1997, an open forum of all participants identified 21 issues of concern to the aquaculture of rock lobsters. These were condensed into five major issues with each major issues condensed examined in detail by a discussion group. One of the five major issues was project management. Based on the range of research issues and other programs related to rock lobsters, well facilitated project management was considered a fundamental priority. With increasing demands being placed on scientists by their host organisations, the role of Sub-program Leader in addition to project commitments can be impossible to fulfil adequately. A dedicated Sub-program Leader will ensure the Sub-program runs effectively and objectives are delivered on time to the industry.

Project 2: COLLECTION AND NEUTRALITY: Before any large scale commercial on-growing of postlarvae is permitted, it will be necessary to establish what effect large scale harvesting of pueruli might have on the wild stock. A second critical need to the success of any commercial venture into rock lobster postlarval growout is that techniques be developed to harvest huge quantities of healthy pueruli. Research is needed to estimate the likely impact of large-scale harvesting of puerulus on the commercial fishery and to establish methods and equipment necessary to catch large quantities of pueruli in the most cost-effective way.

Project 3: NUTRITION: In Australia, opportunities to value add to the wild catch of lobsters or to on-grow juveniles taken from the wild is seriously constrained by the lack of a cost-effective and efficacious rock lobster feed. This contrasts with the developing industry in New Zealand where waste from the large mussel industry is an available and inexpensive source of feed. If feed comprises 40-50% of rock lobster production costs as is the case in other aquaculture industries (prawns, finfish), the development of a suitable manufactured feed is crucial for the successful establishment of rock lobster aquaculture in Australia.

Project 4: HEALTH: Due to the infancy of rock lobster aquaculture, disease conditions associated with production are poorly understood. Similarly, the prevalence of disease conditions in wildstock and their likely impact in aquaculture systems or extended holding systems has yet to be determined. While other factors associated with the establishment of rock lobster aquaculture are perceived as a higher priority, it is recognised that health monitoring and the early identification of diseases that may affect production is critical. In the short term, there is a need to establish a mechanism for the monitoring of disease conditions of juvenile and adult lobsters in land-based and sea-based holding systems. This will not only provide industry with a means of assessment of moribund lobsters, but will facilitate the identification of health research priorities.

Project 5: SYSTEM DESIGN AND HANDLING: Rock lobster fisheries throughout the world are generally fully or over-exploited while market demand remains very high with this product positioned at the premium end of the crustacean market spectrum. The proposed research will assist in increasing supply of this valuable product in a sustainable way and will consequently decrease pressure on wild populations. System design and basic husbandry information must be completed in conjunction with health and nutrition research as these factors combine to influence the efficiency of production.